Failure of an Aluminum Connector in an Electrical Transmission Cable

An 1100 aluminum alloy connector of a high-tension aluminum conductor steel-reinforced (ACSR) transmission cable failed after more than 20 years in service, in a region of consider able industrial pollution. The steel core was spliced with a galvanized 1020 carbon steel sheath. Visual examination showed that the connector had undergone considerable plastic deformation and necking before fracture. The steel sheath was severely corroded, and the steel splice was pressed off-center in the axial direction inside the connector. Examination of the fracture surface and micro-structural analysis indicated that the failure was caused by mechanical overload, which occurred because of weakening of the steel support cable by corrosion inside the fitting. The corrosion was ascribed to defective assembly of the connector which allowed moisture penetration.